Utility ofN-[4-(N-Substituted Sulfamoyl)Phenyl] Cyanothioformamides in the Synthesis of Heterocyclic Compounds

The novel cyanothioformamides 2a-d were prepared by treatment of isothiocyanatosulfonamides 1a-d with potassium cyanide at room temperature. Cyclocondensation of compounds 2b,c with phenyl isocyanate as electrophile furnished the corresponding imidazolidines 3a,b. The reactivity of compound 3a towards some nitrogen nucleophiles was investigated. Thus, the thiosemicarbazone 4 and imidazo[4,5-b]quinoxaline 6 were synthesized by condensation of compound 3a with thiosemicarbazide and o-phenylenediamine, respectively. Treatment of 3a with hydrochloric acid afforded compound 7. Our investigation was extended to include the reactivity of cyanothioformamide 2 towards o-aminophenol, anthranilic acid, and o-phenylenediamine and yielded the corresponding heterocycles 9, 11 and 13 derivatives, respectively. Structures of the synthesized compounds were established by their elemental analysis and spectral data.